1. Field of the invention
The present invention concerns a method of splicing two optical fiber cables.
It applies particularly, but not exclusively, to two ribbon cables each comprising a plurality of monomode fibers.
Such multifiber cables are intended for use in future multiservice optical networks. The jointing of such cables raises problems of cost, optical quality and ease of execution.
Jointing two optical fibers entails dimensional tolerances in the order of one micrometer because of the high degree of confinement of the optical energy. The simultaneous jointing of several pairs of fibers obviously accentuates the difficulty, all the more so in that economic objectives require a low-cost connection device to be used by relatively unskilled personnel under difficult operating and environmental conditions, in particular in trenches.
2. Description of the prior art
At present an operative places the ends of the fibers of each cable in channels etched into one surface of a silicon primary plate; a complementary plate is used to immobilize the fibers. The correct alignment of the two cables requires the use of complex and costly guide means. Guide means are described, for example, in the Pat. No. US-A-3 864 018 or the article by P. STEINMAN in "Fiber and Integrated Optics" vol. 9 pp. 43-52. The primary plates have projections on their outer surfaces cooperating with etched grooves in silicon secondary plates between which the ends of the two cables are sandwiched. These techniques impose severe tolerances on the thickness of the primary plates, the width and the angle of the secondary plate grooves and the spacing between these grooves The ends of each cable must be optically polished by a time-consuming and delicate operation. All aspects of the method are difficult and costly.
An object of the present invention is to enable the process of jointing two optical fiber cables to be considerably simplified.